6.5.1 Hearing Disorders Flashcards
What is the Weber test?
Weber– place tuning fork in center of head
- Normal: sound equal in both ears
- Sensorineural Loss: sound louder in normal ear
- Conductive Loss: sound louder in affected ear
What are the characteristics of audiograms and how are they plotted?
-Plotted with Frequency on X axis and decibels (loudness) on Y axis
-Thresholds are plotted relative to average normal threshold at each frequency
Describe an audiogram for a patient with normal hearing.
How are babies or uncooperative patients tested for hearing?
Objective testing
- Auditory Brainstem Response (ABR): evoked potential measured from scalp
- Otoacoustic Emissions (DPOAE): recorded from small microphone in ear canal. Measure of Outer Hair Cell function (cochlear function)
What is the difference between hearing aids and cochlear implants?
What type of damage can otitis media cause?
Sensorineural hearing loss
If long standing (inner ear damage)
What is auditory brainstem response?
What is the Rinne Test?
Rinne – tuning fork placed on mastoid process (bone cond) and then in front of ear (air cond)
- Normal: will hear sound when fork is moved outside ear, after vibrations stop on bone
- Sensorineural Loss: will hear sound breifly on bone, but will with air (+ Result)
- Conductive Loss: won’t hear sound when fork outside ear (- Result)
What is CGF166 Gene Therapy?
What is air conduction vs bone conduction?
Air conduction: normal route by which airborne sound reaches cochlea - Hearing loss indicates conductive or sensorineural loss
Bone conduction: vibrating probe is applied to skull; vibrations are transmitted directly to cochlea, bypassing the middle ear - hearing loss indicates ONLY sensorineural loss
What is sensorineural hearing loss?
-pathology of inner ear (sensory/cochlea) or CN VIII (neural)
What is Meniere’s Disease?
-Idiopathic endolymphatic hydrops
- Overproduction or inadequate turnover of endolymph
- Puts excess pressure on hair cells
- Symptoms are fluctuating – hearing loss, vertigo, tinnitis, aural fullness
- Long term pressure has potential to cause permanent hearing loss
- Treatment: low salt diet
What are some common causes of conductive hearing loss?
How will you determine whether a patient has conductive or sensorineural hearing loss?
-accomplished by comparison of air and bone conduction thresholds
How is hearing measured in adults?
Subjective testing
- Present tones separately to each ear in a soundproof both
- Vary frequency and intensity
-Determine threshold as a function of frequency
-Determine ability to discriminate speech sounds
What is otoacoustic emissions?
What are the major classes of ototoxic drugs?
These cause damage to inner ear hair cells
Asprin
Aminoglycoside antibiotics
Loop diuretics
Cisplatin
Quinine
What is hearing level?
dB HL = Measured threshold for individual - normal threshold
What is a speech banana?
frequency and HL range important for speech perception (discrimination)
What are some causes of sensorineural hearing loss?
What is the advantage of an audiogram over frequency theshold curves?
Hearing thresholds vary by frequency
What is Central hearing loss?
CNS damage; relatively uncommon
What is a conductive hearing loss?
-impaired conduction of sound through external/middle ear to inner ear
How would an audiogram look for a patient with mixed conductive and sensorineural loss look?
Mixed Loss
- -Bone: increased threshold
- -Air: increased threshold
- -Problem: ext/middle AND inner ear
What is important with children and hearing disorders?
Early diagnosis and intervention is critical
Learning disabilities
Delayed emotional and personality development
What is Tinnitus? Explain Objective vs Subjective.
- Perception of phantom sound that occurs in absence of actual sound (Ringing)
- Often accompanies cochlear hair cell loss (ex: caused by noise damage)
- Objective Tinnitus: true sound produced by pulsation of blood vessel
- Subjective Tinnitus: phantom sound produced by dysfunction in auditory system
- Because it is typically of CNS origin, cutting CN VIII will produce no relief
Hearing thresholds vary by? What range of frequencies can humans hear over?
Frequency
Humans can hear between the ranges of 20-20,000Hz.
How would an audiogram of a patient with conductive hearing loss compare to sensorineural loss?
Conductive Loss
- Bone: normal
- Air: increased threshold
- Problem: ext/middle ear
Sensorineural Loss
- Bone: increased threshold
- Air: increased threshold
- Problem: inner ear
What is Presbycusis?
Aging
High Frequency hair cells are harmed first
Can you describe the characteristics of outer vs inner hair cell loss?
OHCs are more vulnerable than IHCs to damage
Cochlea may have completely normal IHCs, but lack OHCs
IHCs are sensory transducers: loss of IHCs = deafness
OHCs are amplifiers: loss of OHCs = 30-40dB hearing loss
